Does what it says on the tin. I run them with newer stock wheels and a 275/60r20 tire in stock height z71. I haven't rubbed it before, but rub the spacers. I will take a little less than 275 / 55r20. I cranked my t-bars and it still works. Standard wheels do not rub (265/70r17). 275 sticks out, maybe a little too far for my liking, but not by much. See photos. The last photo shows a standard 265 tire and wheel, and it's barely protruding from under the fender. Even on new wheels, the spacer can be seen through wide gaps in the wheel, so maybe reconsider the color you buy if that worries you. These are spacers, so slowly tighten them in a star pattern and you'll be fine. The seal just slips over the stock hub but doesn't seal perfectly so use the star pattern and tapered tabs for everything. I did this and had no vibration at highway speeds. You need someone to step on the brakes so you can tighten the seal properly. If you don't have help, you'll need something to stop the sleeve from rotating to tighten it. The parking brake should hold behind it. After that, don't forget to attach the wheels.